1. Field of the Invention
This invention relates generally to printed circuit boards, and more particularly, it is directed to an edge guide and retainer for printed circuit boards.
2. Description of the Prior Art
Printed circuit boards provide the foundation on which electronic components such as resistors, capacitors, transistors, inductors, semiconductor chips and other discrete electronics are mounted. These circuit boards have the metal traces that provide electrical pathways to connect the electronic components to satisfy an electrical function or system requirement. While each circuit board can accommodate a large number of electronic components, in some applications several circuit boards may be needed to provide the necessary circuitry for the particular electronic product. In such cases, multiple circuit boards may either be mounted in a stacked arrangement, one board on top of the other or in a side by side arrangement. In any case, the board is typically mounted in an electronic chassis, being plugged into a card receiving connector at one end and guided by card guides along two side edges.
Such card guides conventionally take the form of a rail with a squared channel therein. The card guides are typically made of nonconductive materials such as plastic. While these conventional card guides are suitable for various applications, growing concerns about electromagnetic interference, radio frequency interference and electromagnetic contamination within electronic environments are necessitating reliable circuit board grounding solutions. Additionally, build up of electrical charges in the circuit card can result in damage to or ultimate failure of internal integrated semiconductor circuits or other circuit elements on the card as well as the electronic apparatus itself. Grounding may be particular important in application involving computer peripherals, accessories and removable media including hard drives, modems and external storage units. In order to mitigate the above problems, various grounding schemes have evolved. Circuit cards have been provided with conductive grounding contacts along the peripheral edge of the card in fixed locations. Cooperative grounding contacts such as clips or terminals are provided on the card-receiving connector or card guides. When the circuit card is slid into the card guide the circuit card grounding contacts line up and mate with the clips on the card guide providing a grounding pathway therebetween
While such conventional grounding schemes have been used in industry for many years, it would be advantageous to provide a grounding arrangement for the card receiving connector or card guides that could accommodate grounding contacts on various locations along the edge of a circuit card. Such a universal grounding clip arrangement that is also simple to manufacturer in large quantities and that provides a reliable grounding solution would provide an advancement in the art.
The foregoing mentioned disadvantages are avoided by a circuit board edge guide which has a grounding strip along its entire length. The edge guide has a squared channel adapted to guide a circuit card to its desired mounting position which typically is a connection with a card-receiving edge connector. A conductive grounding strip is mounted on the edge guide in the squared channel for engaging the edge of the circuit board and making electrical contact with any grounding contacts on the board""edge. Accordingly, advantageously with the above described grounding arrangement provided along the extent of the edge guide, this circuit board edge guide can work with a variety of circuit cards with grounding contacts in various locations along the edge thereof.
The invention contemplates that the grounding strip be constructed as a universal structure for mounting on a variety of circuit board edge guides by simply clipping on. In the preferred embodiment, the grounding strip is formed from stainless steel having an elongated section, each end thereof having short integrally formed clips. As such, the grounding strip can simply be placed in the guide channel with the clips at ends clipped over the ends of the edge guide. Surprisingly, this simple grounding arrangement reliably affixes securely to the edge guide. Furthermore, the relative simplicity of this arrangement allows the edge guide and grounding strip to be made in large quantities and easily assembled.
The construction and operation of a preferred embodiment of the circuit board edge guide of the present invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings.